Final answer:
The statement that her mother sings with 'velvety lungs that powerful as morning glories' is an example of a metaphor.
Step-by-step explanation:
A metaphor is a figurative use of language in which one thing is compared to another without using the words 'like' or 'as.' In the given statement, the comparison between the mother's voice and morning glories is described without using a direct comparison or the words 'like' or 'as,' so it is not a simile. Therefore, the statement is an example of a metaphor.